This application claims the priority of German Patent Document 100 47 012.2, filed Sep. 22, 2000, the disclosure of which is expressly incorporated by reference herein.
The invention relates to an internal combustion engine with turbocharger and exhaust gas temperature regulation, wherein the torque is adjusted so that the full-load torque desired by the driver and, at the same time, a fuel consumption that is as low as possible, are obtained even under changed operating conditions.
The problematic and the influence of the load pressure on the engine torque or the changes of the available torque when a change of the operating conditions occurs is already known from German published patent application 195 19 381. A device is described therein, which controls or regulates the engine torque depending on a multitude of influence variables in such a way that the device lowers the load pressure depending on a preset desired engine torque when the desired engine torque, or a desired operating variable of the engine connected therewith, is less than a corresponding given operating variable of the engine without intervention on the load pressure. By utilizing a preset desired engine torque as a control or regulation variable for the engine torque, a multitude of vehicle influence variables can be taken into consideration. It is also designed so that the reduction of filling in the cylinders produced by the load pressure drop has as a consequence a drop of the exhaust gas temperature.
Essential criteria for controlling the different operating cycles of an internal combustion engine are a high driving comfort together with a fuel consumption that is as low as possible, and an improvement of the environmental compatibility. In internal combustion engines with turbocharged engines, the exhaust gas temperature regulation is one possibility of meeting these requirements. In systems with exhaust gas temperature regulation, the engine is usually operated with a stoichiometric mixture until a maximum permissible temperature is reached. After exceeding a defined temperature limit value, a mixture enrichment is undertaken, which keeps constant or lowers the exhaust gas temperature and, as a consequence, the temperature of the components via the open circuit cooling which takes place. As a rule, the mixture enrichment effects an increase of the available torque.
The process according to the invention has the advantage that, in internal combustion engines with turbocharger and exhaust gas temperature regulation, the maximum torque remains constant independently from the mixture composition, and therefore the driving performance and the driving comfort are fully maintained. The inclusion of the lambda efficiency factor in the determination of the control variables, and especially in the determination of the filling capacity, effects an optimal tuning of the consumption-optimized operation.
Further advantageous improvements of the process according to the invention are possible via the measures described herein.
The respective operating conditions are taken into consideration because the correction of the maximum filling capacity (rlmax) taken from the characteristic field is carried out by forming the quotient from the maximum filling capacity (rlmax) taken from the characteristic field and the value for the lambda efficiency factor (ETA-LAM) and a value for the corrected filling capacity (rl-korr) is obtained as a result.
A weighing of the value for the corrected filling capacity based on further demands placed on the internal combustion engine such as, for example, knock control and limiting stages, and the corresponding modification also have the advantage of controlling the operation of the internal combustion engine as optimally as possible in accordance with the current requirements.
The embodiments of the invention are shown in the drawings, which are described in more detail in the following, and wherein:
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.